SANAA, Yemen — Yemenis flocked to the polls across their battered nation Tuesday to vote in a U.S.-backed, single-candidate election meant to instate a new leader to replace the outgoing autocrat.

Vice President Abed Rabbo Mansour Hadi is set to be declared president in the coming days, which will make his predecessor, Ali Abdullah Saleh, the fourth leader to be pushed from power in the Arab Spring uprisings that erupted early last year.

While the voters were largely hopeful — with some waiting in long lines to cast ballots bearing only Hadi’s name — the new leader will face tremendous challenges as he tries to lead the Arab world’s poorest country out of its year-old political crisis, which has shattered the economy, splintered the security forces and allowed al-Qaida to seize swaths of territory.

The U.S. has played an active role in the transition, in hopes it can head off chaos and ensure cooperation against the country’s active al-Qaida branch, which has targeted the U.S.

Story continues below advertisement.

President Barack Obama voiced his support for Hadi before the vote, and the administration’s top counterterrorism adviser, John Brennan, met Hadi in Yemen over the weekend and said he expected him to be a strong partner.

In taking Saleh’s place, Hadi will face the onerous task of trying to lead Yemen out of its many crises. Yemen was a poor, weakly governed nation before protesters inspired by successful uprisings in Tunisia and Egypt took to the streets one year ago to call for Saleh’s ouster.

The situation now is much worse. More than 200 protesters have been killed in government crackdowns, and hundreds more have died in armed clashes with security forces. Meanwhile, the country’s economy has collapsed, with unemployment and food prices spiking.

Hadi promised great changes Tuesday said after casting his vote in the capital Sanaa.

“This is a qualitative leap for modern Yemen,” he said. “There will be big political, economic and social change, which is the way out of the crisis that has ravaged the country.”

The election, however, masks how many deeply entrenched problems remain unchanged, said Yemen expert Gregory Johnsen of Princeton University.

“There is this sense that Saleh was at the root of all the problems in Yemen and that removing him from the office of the president is going to miraculously solve Yemen’s problems, but it will not,” he said. “None of the issues that were brought to the forefront over the past year have been solved, and all of the players who are intimately involved with them are still involved in politics.”

Saleh used his decades in office to put relatives, confidantes and fellow tribesmen in key places in the government and security apparatus. They remain, meaning that Saleh could continue to pull strings in Yemen without being president. Hadi could also face great resistance to reform from these entrenched forces.

Yemen’s army is splintered, with many soldiers more loyal to their commanders than to the state. It remains unclear what leverage Hadi will have to create a unified command.

The U.S. and Yemen’s powerful Gulf neighbors, especially Saudi Arabia, were instrumental in pushing the deal to bring Hadi, who they hope will fight al-Qaida.

Some voters voiced similar hopes, especially those displaced by fighting.

“My only demand is that Hadi work to solve our problem with al-Qaida, peacefully or through war,” said voter Hamdoun Mehdi, a teacher. He cast his ballot in the southern city of Aden, one of tens of thousands who fled parts of nearby Abyan province when al-Qaida came in last spring.

Underlining the fragile security situation, seven people were shot dead outside polling stations in southern provinces. They included three soldiers, a woman and a child.

In Aden province, unknown gunmen seized 44 ballot boxes out of some 800 total, said the region’s electoral chief, Abdel-Aziz Yehiya. It was unclear who took the boxes, but al-Qaida operates nearby, as does a movement calling for independence for the south.

Nationwide, the national election commission said it halted the vote in nine electoral districts out of 301 for security reasons.

Yemen will be the fourth country to have its leader pushed out in the Arab Spring uprisings. It will also have the least immediate political change.

Tunisia convicted in absentia former president Zine El Abidine Ben Ali of corruption. He remains in exile. Egypt is trying ousted leader Hosni Mubarak for his alleged role in killing protesters. And rebel fighters captured and killed Libyan strongman Moammar Gadhafi last October.

Saleh, however, is leaving power as part of a U.S.-backed deal that grants him immunity from prosecution. He is currently in the U.S. seeking treatment for burns sustained during a bomb blast in his palace mosque last June. He is expected to return to Yemen soon, where he has said he could remain involved in politics.

Some Yemenis questioned the value of voting in a single-candidate election in which even those casting ballots could not vote no.

“It’s like a stupid play,” said Sanaa shopkeeper Aaid Marzouq.

But many seemed glad to participate, either because they hoped it would help bring stability or because it was the only way to ensure Saleh’s departure.

About 10 million of Yemen’s 24 million people are registered to vote, but turnout figures were not immediately available. A large turnout could bolster Hadi’s mandate.

Sanaa resident Bushra al-Baadany brought her son to cast her vote.

“I am voting for Hadi as a new leader instead of Saleh because I want change,” she said. “If Hadi is like Saleh, we are ready to have another revolution.”